JPS6054404B2 - Method for producing self-extensible polyester staple fiber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for industrially producing polyester staple fibers that undergo irreversible self-extension at 180°C±20°C.

It is widely practiced to produce bulky spun yarn by blending two or more types of staple fibers with different shrinkage properties. After making the spun yarn into a woven or knitted fabric,
By heat-treating at around 180° C., the bulk is increased due to the difference in shrinkage between the two staple fibers.

However, such spun yarns have the property that their texture becomes hard and the application method changes (decreases) by heat treatment, so there is a problem that their uses are naturally limited. To solve these problems, it is possible to use self-extensible staple fibers instead of high-shrinkage staple fibers, but there is still no way to industrially produce self-extensible polyester fibers for staple fibers. unknown. That is,
Several methods for producing self-extensible polyester multi-layer filament yarns have been proposed, but even if these methods are directly applied to the production of staple fibers, there are problems in process conditions, product properties, uniformity, etc. For this reason, the present inventors have conducted repeated research on a method for industrially producing self-extensible polyester stable fibers, and have found that undrawn polyester fiber bundles obtained by high-speed spinning are stretched under specific conditions to further relax them. By heat treatment,
The present invention was achieved by discovering that it is possible to produce a self-extensible polyester stable fiber suitable for use in bulky spun yarn.

That is, the present invention provides birefringence (Δn) obtained by high-speed spinning.
A polyester undrawn fiber bundle of 0.02 to 0.08 [
Glass transition point temperature (Tg°C) + 20°C] or less, and stretched to the following draw ratio (DR), and then subjected to relaxation heat treatment at a temperature of 100 to 140°C for 10 minutes or more to 180°C ± 20
There is a method for producing a self-extensible stable fiber characterized by obtaining a stable fiber exhibiting irreversible self-extensibility at 'C.

The term "polyester" used in the present invention mainly refers to polyester terephthalate, but it is also a copolyester in which a small amount of a third component (for example, a metal salt of sulfoisophthalic acid) is copolymerized to improve dyeing properties, anti-build properties, etc. It's okay.

Further, the polyester may contain additives such as matting agents, colorants, and modifiers. Degree of polymerization of the polyester -
varies depending on the required characteristics and application of the product stable fiber, but generally the intrinsic viscosity of the raw material polymer (35℃, o
- in chlorophenol) from 0.5 to 0.7 is preferred. In the present invention, a fiber bundle (tow or saft tow) is made of undrawn polyester fibers having a birefringence index (Δn) of 0.02 to 0.08, preferably 0.04 to 0.07, obtained by spinning such polyester at high speed. use.

The single yarn denier of the fiber bundle is preferably 3 c1e or less, and the total denier is suitably 10,000 to 100,000 deni 5 l from the viewpoint of productivity. Such fiber bundles are made by spinning polyester, especially polyethylene terephthalate, at a take-up speed of 2000.
m. It can be easily produced by spinning at a high speed of 1 minute or more, especially 3000 to 4000 m, and any known spinning device can be used as long as it can perform high speed spinning at the above speed. It is possible.

In the present invention, an appropriate number of fiber bundles having the above-mentioned birefringence index are bundled, supplied to a drawing process, and drawn using dry heat or wet heat.

This stretching is performed at the glass transition temperature (T) of the polyester fiber.
It is carried out at a temperature of [Tg+20°C] or lower depending on the temperature (g°C).
The Tg of polyethylene terephthalate fiber is said to be 70°C, but in water the Tg is approximately 20°C lower than this, so the temperature should be 90°C or lower for dry heat drawing and 70°C or lower for wet heat drawing. It should be adopted. According to the research conducted by the present inventors, it is particularly preferable to carry out the stretching in a hot water bath at 40 to 70° C. from the viewpoint of both the stretching condition and the uniformity of the product. The draw ratio (DR) must be selected in accordance with the birefringence index (Δn) of the undrawn fibers so as to satisfy the following formula.

DR that satisfies the range of this formula is indicated by the shaded area in FIG.

Figure 1 is a graph showing the relationship between DR and Δn, where the curve A in the figure represents DR=0.04/Δn+1.1, and the curve at the mouth represents DR=0.04/Δn+0.7. show.

In addition, in the figure, the ○ mark or the × mark indicates the intrinsic viscosity [η
] of 0.64 using a spinneret with 720 holes.
．． Melt-spun at a speed of 1 minute to obtain ΔNflfO. Ol8～0
．． 085 undrawn yarn was obtained, and then the undrawn yarn was bundled into a 500,000 denier tow, and the fiber properties and stretching time of stable fibers obtained by performing various stretching ratios at a stretching temperature of 50 ° C. The results are shown regarding the process condition.

Here, the O mark indicates the level of R, which indicates that both the process condition during stretching and the fiber physical properties of the obtained stable fiber are good;
The x mark indicates a DR level at which the process condition during stretching or the fiber physical properties of the resulting stable fiber are poor.

If the drawing is done at a higher DR than the curve A in the figure, yarn breakage will easily occur during drawing, and the stable fiber obtained will also be 1
It no longer shows self-extension at 80°C.

On the other hand, if the fiber is drawn at a lower DR than the mouth curve, the process condition during drawing is good, but the physical properties, especially the strength, of the resulting stable fiber deteriorates and troubles are more likely to occur during the spinning process.

Furthermore, if Δn of the undrawn yarn is less than 0.02, the resulting stable fiber will not exhibit self-extensibility at 180°C but will exhibit shrinkage, and if Δn exceeds 0.08 Yarn breakage occurs frequently during stretching.

In this way, by employing the DR shown in the shaded area in the figure, the stable fiber that is the object of the present invention can be obtained for the first time.

Note that even if the drawing is performed using the DR shown in the shaded area, the drawing temperature is set to [T].
g+20°C], the resulting stable fibers no longer exhibit self-extensibility.

The drawn fiber bundle is crimped if necessary and subjected to relaxation heat treatment.

It is necessary that the relaxation heat treatment temperature be 100 to 140°C, and if it is outside this temperature range, the self-extensibility that is the object of the present invention cannot be obtained. It is industrially advantageous to carry out the heat treatment by placing the fiber bundle on a wire mesh conveyor or the like and blowing heated air through it. However, it is also possible to employ other relaxation heat treatment means, and the relaxation heat treatment can be performed after cutting the fiber bundle to form stable fibers.
The heat treatment time is 10111- or more, preferably 10-60
It is necessary to give enough contraction. If the heat treatment time is less than 1 piece, the self-elongation rate at 180° C. will vary greatly, and defects such as streaks will easily occur in the final woven or knitted fabric. The fiber bundle may be cut into stable fibers either before or after the relaxation heat treatment, and the length of the cut fibers can be appropriately selected depending on the application. According to the present invention as described above, a polyester stable fiber that exhibits irreversible self-extension when heat-treated at 180°C ± 200°C can be produced in a stable process condition, and the stable fiber can be made from ordinary polyester fibers. By blending it with table fiber or other types of fibers (wool, cotton, acrylic fiber, etc.) to make a spun yarn, and heat-treating this after weaving and knitting, it is possible to make a bulky knitted fabric with a soft and pleasant texture. Next, embodiments of the present invention will be described in detail.

Example 1 Polyethylene terephthalate having an intrinsic viscosity [η] of 0.64 was melt-spun using a spinneret with 720 spinning holes at a spinning take-off speed of 3500 ml.

The polyester fibers constituting the obtained subtow had a birefringence index (Δn) of 0.05\\single polyethylene terephthalate fibers of 1. It was distributed by e. This sub-tow was bundled into a tow of 500,000 denier, stretched in a hot water bath at the stretching temperature Tdl shown in Table 1, and crimped with a push crimper. 1 at the temperature Ts・shown in
The fiber was subjected to a relaxation heat treatment and then cut with a cutter to obtain a stable fiber.

Dry heat each stable fiber at 180°C.
Table 1 shows the results of the heat treatment.

Next, Table 1 Experiment No. 2 (before final treatment) and a commercially available polyester stable fiber at a weight ratio of 50/50 to produce a spun yarn, and a fabric woven using the spun yarn was woven at 180°C into three powders. Heat treated for a while.

The obtained woven fabric had excellent bulkiness and a soft feel. Example 2 Experiment No. 1 of Example 1 was used except that the relaxation heat treatment time was changed as shown in Table 2. A stable fiber was obtained in the same manner as in 2.

Each of the obtained stable fibers was dry heated at 180℃.
'C for 15 minutes, and the average value (X) and variation rate (CV) of the self-elongation rate were determined for each stable fiber.

The results are shown in Table 2. Further, the fabric was evaluated in the same manner as in Example 1, and the results are also shown in Table 2. Experiment No. Since the stable fiber of No. 12 was not sufficiently subjected to relaxation heat treatment, the self-elongation rate varied widely, and streaks occurred in the resulting fabric. In contrast, experiment No. 1 in which one or more particles were subjected to relaxation heat treatment. l3 and 14
In this case, since sufficient heat treatment was performed, there was little variation in the self-elongation rate, and the resulting fabric had excellent bulk and a soft feel. Comparative Example When the spinning take-off speed was 50007TL1 minute, the birefringence (
Experiment No. 1 of Example 1 was performed, except that a polyester fiber with Δn) of 0.080 was obtained and then stretched at a stretching ratio of 1.8 times.
A stable fiber was obtained in the same manner as in 2.

Under such stretching conditions, yarn breakage occurred, and when the resulting stable fiber was subjected to a dry heat treatment at 180° C., it showed a shrinkage of 2%.

[Brief explanation of the drawing]

Figure 1 is a graph showing the relationship between DR and Δn, where the curve A in the figure represents DR=0.04/Δn+1.1, and the curve at the mouth represents DR=0.04/Δn+0.7. show.

Claims (1)

[Claims] 1. Birefringence (Δn) obtained by high-speed spinning: 0.02 to 0
．． The undrawn polyester fiber bundle of No. 08 was stretched at the following stretching ratio (
DR), (0.04/Δn)+0.7≦DR≦
(0.04/Δn)+1.1 then 100-140℃
Relaxation heat treatment at a temperature of 180℃±20 for 10 minutes or more
A method for producing self-extensible polyester staple fibers, characterized by obtaining staple fibers that exhibit irreversible self-extension at °C. 2 Birefringence of undrawn polyester fiber is 0.04 to 0
．． 07. The manufacturing method according to claim 1. 3 Single yarn denier of undrawn polyester fiber bundle is 3de
The manufacturing method according to claim 1, which is as follows. 4. The manufacturing method according to claim 1, wherein the stretching is carried out in a hot water bath at 40 to 70°C. 5. The manufacturing method according to claim 1, wherein the relaxation heat treatment is performed using heated air.